The present invention relates to a hydrocarbon dispenser nozzle and, more particularly, to an improved control system for the nozzle which prevents unauthorized dispensing of hydrocarbon as well as unintended spillage thereof.
Hydrocarbon dispenser nozzles are becoming more and more complex, firstly to avoid unwanted flows of hydrocarbon under various circumstances, and secondly to avoid various types of fraud being perpetrated by the user.
The risk of unwanted hydrocarbon flow occur in particular under the following two circumstances:
Firstly, when the nozzle is in its rest position with its orifice pointing upwards, the hose associated with the nozzle is always kept under pressure even when the pump is stopped. If a leak occurs in this position because of the pressure, then the hydrocarbon spreads over the handle of the nozzle and this is naturally very disagreeable for the user.
Secondly, when a user takes hold of the nozzle in certain types of installations, there may be relatively high pressure in the hose. In this case there may also occur a flow of hydrocarbon.
One known fraud, applicable to a nozzle that includes a downstream valve that opens under pressure, consists of jumping on the hose of the nozzle to create excess pressure that will give rise to fraudulent opening of the valve.
The solutions generally used for avoiding such unwanted flows of hydrocarbon or for preventing such fraud involve either increasing the force of the return spring on the valve or else using an upstream valve that tends to close with increasing pressure.
In both cases, the force the user needs to exert on the trigger of the dispenser nozzle to obtain hydrocarbon delivery is very significantly increased. This can create difficulties with certain categories of user.
Another way in which unwanted flow of hydrocarbon may happen occurs when the user withdraws the nozzle from the vehicle tank after filling the tank. The fraction of hydrocarbon that remains in the cavity between the valve and the end of the nozzle tube can be considerable, and depends on the angle of inclination of the tube, and this volume may spill out under gravity onto the ground when the user removes the nozzle from the tank of the vehicle.